Got to work this morning after running the defroster on high, turned the key off and the speakers popped, like a static discharge or a high-power amp powering up. I turned the key back on and off several times and it still happened. Started it up to come home and everything was normal. Got home after running the defroster on high all the way and the problem happened again.

After the truck cab cooled off the problem went away again???? It almost seems like the radio was getting too hot. I did a search and only one thread had the word speaker.

2008 f150 4x4 4.6 am/fm single cd factory radio

I replaced my head unit with an aftermarket one and I can tell you that I've never experienced that. It does sound like it is due to the head unit though. You might have a short or exposed wire in that thing somewhere.

Ryan

I did some googling and found this. I didn't notice if my radio was locked up, but this sounds like the exact symptoms I have. Looks like a quick ACM replacement is necessary as the 2008 f150 acm cannot be reprogrammed.

http://mygtcs.com/mustang/documents/tsb/tsb09-20-10.pdf

TSB
09-20-10 SPEAKER POP AND/OR RADIO INOPERATIVE/BLANK/LOCKED UP

Publication Date: September 30, 2009

FORD: 2008-2009 Fusion, Mustang
2008 F-150
2008-2009 Edge, Expedition, Explorer Sport Trac, Explorer, F-Super Duty
MERCURY: 2008-2009 Milan, Mountaineer


This article supersedes TSB 9-16-3 to update the vehicle lines.

ISSUE:
Some 2008-2009 F-Super Duty, Expedition, Explorer, Explorer Sport Trac, Mountaineer, Fusion, Milan, Mustang,, Edge and 2008 F-150 vehicles equipped with Single CD and CDX6 Audio Control Modules (ACM), may exhibit either a speaker pop noise and/or a condition where the ACM is completely inoperative or will not power on.

ACTION:
Follow the Service Procedure steps to correct the condition.

SERVICE PROCEDURE

The speaker pop typically happens after an extended drive period when vehicle is warm and opening/closing a door; however, it may happen anytime the (ACM) is turned off. Using the vehicle heater through the instrument panel (IP) panel vents (on high setting) may also cause the condition to repeat more often. The ACM may be completely inoperative, blank. or locked up. It may be caused by a software lockup event within the ACM.

Reprogram the ACM to the latest calibration using IDS 63.02 and higher. This new calibration is not included in the VCM 2009.9 DVD Calibration files may also be obtained at www.motorcraft.com.

An ACM replacement will be necessary for 2008 F-150 for the above symptoms, it can not be reprogrammed with IDS. Reference Workshop Manual, Section 415-00 for removal and installation instructions. Please specify speaker pop noise/lock up on the 1878 form when ordering a replacement ACM for F-150.


WARRANTY STATUS:
Eligible Under Provisions Of New Vehicle Limited Warranty Coverage
IMPORTANT: Warranty coverage limits/policies are not altered by a TSB. Warranty coverage limits are determined by the identified causal part.

OPERATION DESCRIPTION TIME
092010A 2008-2009 F-Super Duty, Expedition, Explorer, Mountaineer, Explorer Sport Trac, Edge, Fusion, Milan, Mustang: Reprogram The ACM
092010B 2008 F-150: Retrieve The ACM Unit Part Number - Acquire And Order An Exchange Unit Can Be Claimed with Operation C
092010C 2008 F-150: Replace The ACM